1978 OMC w/ 305 power plant 1st question

Greetings everyone.
I am looking at purchasing a 1978 SeaEagle with a 305 engine and an OMC sterndrive. I believe it is a mechanical shift, but how can I tell for sure?
Second question, the owner says all the oil drained out of the sterndrive while it was sitting in his driveway. It has been sitting in his driveway for 5 years and one year all the oil drained out. The weird part is that he showed me all the oil drained out of hole at the top of the drive? Then he tells me the OMC mechanic wants $1,800.00 to repair it quoting all new seals?
Is there an upper and lower gearcase and two different levels?
I really like this boat but don't want to buy a pile of junk. I have extensive mechanical ability and just finished putting my Mercruiser outdrive back together. I have machine shop access and a big shop. Years of experience as a mechanic and a machinist so I'm not helpless. Looking for a little guidance.
Thanks Everyone
Dan

I read your first sentence only, and I stopped reading.
In 1978, this would be an OMC "stringer drive". While I do not care for any OMC product, the stringer drive is definitely one to avoid, especially these days!

I would strongly encourage you to look for another boat with perhaps a MerCruiser stern drive or a Volvo Penta sterndrive.


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Really? After doing a bellows job on this Mercruiser, I am hard pressed to find anything more poorly designed from a maintenance standpoint.

My apologies Recardo. Thank you for your reply.
I understand buying something else is probably the right thing to do, but I am rich with skill and short on money. I like this boat for many reasons, but have serious reservations about the OMC drive.

78 was hydromechanical shift, a design so bad OMC recalled it and replaced the lower units on some with a full mechanical unit under warranty (including the install of an ESA shift interrupt system). It takes a fair comprehension of all the generations to know which is on that boat and whether the conversion to full mech was done properly. Some people just throw a mechanical lower on when the hydromech lower inevitably craps out.
That might be a good boat for someone like me that has a shed full of spare parts, lots of experience fixing them and never moors the boat.
But I have a Mercruiser Alpha.

Saying Merc design sucks because the bellows are stupid might be true, but it doesn't make other brands any better.

Save up for something better.

catalina0029 said:

Really? After doing a bellows job on this Mercruiser, I am hard pressed to find anything more poorly designed from a maintenance standpoint.

Click to expand...

Well, let's not call it poorly designed quite yet!

Both Merc (w/ thier A drives) and OMC (w/ their Cobra drives) used Gimbal System suspension.
This design creates the need for a Gimbal Bell and Gimbal Bearing, of which does make accessing the drive shaft bellows more time consuming and difficult.
These also incorporate a rubber hub drive coupler which requires annual engine alignment. These couplers do occasionally fail, and do require engine removal for replacement.
The SI or SA and ESA are required for the Dog Clutch gear dis-engagement.


The AQ series Volvo Penta cone clutch drives, with main suspension fork/pivot tube geometry, allows these to be much easier to service. Very user friendly!
These use fixed PDS geometry with an all steel drive coupler, of which means no annual alignment check.
No SI or SA nor ESA required with cone clutch engagement.



Perhaps use this info to help choose another boat.

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